Magnetic fields above the surface of a superconductor with internal magnetism

TL;DR

This paper develops a method to calculate magnetic fields near superconductors with internal magnetization, aiding the analysis of magnetic scanning experiments and understanding domain structures.

Contribution

It introduces a new calculation approach for magnetic fields above superconductors with intrinsic magnetization, including spectral density relations and solutions for domain configurations.

Findings

Domain walls would be detectable with current methods.

Random small domains produce fields below noise levels.

Results assist in interpreting magnetic scanning data.

Abstract

The author presents a method for calculating the magnetic fields near a planar surface of a superconductor with a given intrinsic magnetization in the London limit. He computes solutions for various magnetic domain boundary configurations and derives relations between the spectral densities of the magnetization and the resulting field in the vacuum half space, which are useful if the magnetization can be considered as a statistical quantity and its features are too small to be resolved individually. The results are useful for analyzing and designing magnetic scanning experiments. Application to existing data from such experiments on Sr$_2$RuO$_4$ show that a domain wall would have been detectable, but the magnetic field of randomly oriented small domains and small defects may have been smaller than the experimental noise level.